Rotary developing device having adjustably mounted developing units

Abstract

A rotary developing device which facilitates a positional adjustment of developing units and prevents the developing units from being shifted even when they are used for a long period. Pins protruding from a revolver are inserted into elongated holes formed in developing units so that developing units are held in such a manner that the developing units are movable relative to the revolver. By mounting a spacer between the elongated hole and the pin, the positional adjustment of the photosensitive drum and the tracking roller is completed. Furthermore, a plurality of spacers which differ in thickness are prepared and by merely selectively mounting an appropriate spacer, the position adjustment of the tracking roller is completed.

What is claimed is: 
     
       1. A rotary developing device comprising: a plurality of developing units, each developing unit including a developing member that develops an electrostatic latent image formed on a photosensitive body and tracking members located on ends of the developing member that come into contact with the photosensitive body to make a distance between the developing member and the photosensitive body constant;   a revolver that rotates while holding the plurality of developing units;   holding means for adjustably holding the plurality of developing units on the revolver so that the plurality of developing units are movable relative to the revolver in an approximately radial direction of the revolver; and   adjustment members that are replaceably mounted on the holding means and that adjust positions where the tracking members start contacting with the photosensitive body.   
     
     
       2. A rotary developing device according to claim 1, wherein a mounting and dismounting position of the adjustment members is located at a replacement position of a toner cartridge of the plurality of developing units. 
     
     
       3. A rotary developing device according to claim 2, wherein: the holding means comprises a support member that protrudes from one of the revolver and the developing units, and an elongated hole formed in the other of the revolver and the developing units and through which the support member is inserted; and   each of the adjustment members includes a spacer mounted between the elongated hole and the support member to define a distance between one end of the elongated hole and the support member.   
     
     
       4. A rotary developing device comprising: a plurality of developing units, each developing unit including a developing member that develops an electrostatic latent image formed on a photosensitive body and tracking members located on ends of the developing member that come into contact with the photosensitive body to make a distance between the developing member and the photosensitive body constant;   a revolver that rotates while holding the plurality of developing units;   holding means for adjustably holding the plurality of developing units on the revolver so that the plurality of developing units are movable relative to the revolver in an approximately radial direction of the revolver; and   adjustment members that are mounted on the holding means and that adjust positions where the tracking members start contacting with the photosensitive body;   wherein a mounting and dismounting position of the adjustment members is located at a replacement position of a toner cartridge of the plurality of developing units.   
     
     
       5. A rotary developing device comprising: a plurality of developing units, each developing unit including a developing member that develops an electrostatic latent image formed on a photosensitive body and tracking members located on ends of the developing member that come into contact with the photosensitive body to make a distance between the developing member and the photosensitive body constant;   a revolver that rotates while holding the plurality of developing units;   each of the plurality of developing units is held to the revolver by a support member that protrudes from one of the revolver and the developing units, and by an elongated hole formed in the other of the revolver and the developing units and through which the support member is inserted such that each of the plurality of developing units is movable relative to the revolver in an approximately radial direction of the revolver; and   a spacer mounted between the elongated hole and the support member to define a distance between one end of the elongated hole and the support member to adjust positions where the tracking members start contacting with the photosensitive body.   
     
     
       6. A rotary developing device according to claim 5, wherein a plurality of said spacers which differ in thickness are provided. 
     
     
       7. A rotary developing device according to claim 5, wherein a thickness of said spacer can be determined while being mounted between the support member and the elongated hole. 
     
     
       8. A rotary developing device according to claim 5, wherein said spacer is provided with an elastically deformable pawl piece which is engaged with said developing unit. 
     
     
       9. A rotary developing device according to claim 5, wherein said spacer is provided with a peripheral wall which comes into contact with and surrounds an outer peripheral portion of said elongated hole. 
     
     
       10. A rotary developing device according to claim 5, wherein a mounting and dismounting position of the spacer is located at a replacement position of a toner cartridge of the plurality of developing units. 
     
     
       11. A rotary developing device according to claim 5, wherein the spacer is replaceably mounted between the support member and the elongated hole.